There are many anatomical geometrical changes between one individual and another. A joint shape can vary between individuals and even between the joints in the same individual. Devices that are designed to be inserted into a certain joint space should therefore include means to adapt the geometry to suit the particular joint. For example, a device may have a straight shape, and as it is forced into the joint space, it must bend according to the arcuate joint space.
However, the insertion of the device into the joint space may require application of impact in order for the device to enter the joint space. The application of the impact may cause the device to bend before it properly enters the joint space. This may cause the procedure to fail, either because the bending of the device prevents its entry or the device may break as it bunches or buckles upon entry into the body lumen.